Production device and method of epoxypropane

Abstract

The invention relates to an epoxypropane production device which comprises a reaction system, the reaction system comprises a fluidized bed reactor, a feeding pipe, a separator and a catalyst regenerator, the separator is communicated with the upper end of the fluidized bed reactor, and the catalyst regenerator is communicated with the lower end of the separator; the lower end of the catalyst regenerator is communicated with the lower part of the fluidized bed reactor, the feeding pipes are communicated with the lower end and the side part of the fluidized bed reactor, and the feeding pipes are uniformly communicated with the side part of the fluidized bed reactor at intervals; the propylene separation system is communicated with the separator and the feeding pipe; the propylene oxide purification system is communicated with the propylene separation system; the methanol recovery system is communicated with the propylene oxide purification system, and the methanol recovery system is also communicated with the feeding pipe. The reaction rate is uniform and controllable, the local hot spot phenomenon can be avoided, and the epoxypropane selectivity is high.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to the production of propylene oxide. Background Art

[0002] Propylene oxide (PO) is an important propylene derivative, mainly used in the production of polyether polyols, propylene glycol, propylene glycol ether, isopropanolamine, propylene carbonate, etc. It is one of the main raw materials for the manufacture of polyurethane, non-ionic surfactants, emulsifiers, oilfield demulsifiers, flame retardants, plasticizers, lubricants, etc. It is widely used in the petroleum, chemical, pesticide, textile, daily chemical and other industries.

[0003] At present, the main methods for producing PO include chlorohydrin method, co-oxidation method and direct oxidation method with hydrogen peroxide (HPPO method). Chlorohydrin method has large discharge of three wastes, serious environmental pollution and great difficulty in comprehensive treatment, and has been listed as restricted development. Co-oxidation method includes isobutane co-oxidation method and ethylbenzene co-oxidation method, which respectively co-oxidize isobutane or ethylbenzene with propylene to produce PO, and simultaneously co-produce tert-butyl alcohol (TBA) or styrene (SM). The main disadvantages of this method are high equipment investment cost, complex process flow, high requirements for raw material purity, a large number of co-products in the production process, and economic efficiency is seriously dependent on the market demand and price of co-products. HPPO method uses propylene and industrial hydrogen peroxide as raw materials, and directly oxidizes to produce propylene oxide under the catalysis of titanium silicon molecular sieve catalyst. The process flow is simple, the reaction conditions are mild, the whole production process has no harmful gas emissions, and the wastewater produced can meet the discharge standards after general treatment. Its advantages of green environmental protection and low production cost have made it one of the fastest-growing and most promising processes.

[0004] However, the current industrialized HPPO process devices all use a tube-in-tube fixed-bed reactor. The reaction is difficult to control and is prone to "temperature runaway" locally, resulting in poor reaction selectivity, many by-products, a large amount of hydrogen peroxide decomposition, a high oxygen content in the exhaust gas, a high potential risk of combustion and explosion, and a shortened service life of the epoxidation catalyst, which needs to be regenerated every one to two months, seriously affecting the economic benefits of the enterprise. Summary of the invention

[0005] The embodiments of the present application provide a device and method for producing propylene oxide to solve the technical problems that the current HPPO method for producing propylene oxide is difficult to control and prone to "temperature runaway" locally.

[0006] In a first aspect, an embodiment of the present application provides a production device for propylene oxide, the production device for propylene oxide comprising:

[0007] A reaction system, the reaction system comprising a fluidized bed reactor, a feed pipe, a separator and a catalyst regenerator, wherein the separator is connected to the upper end of the fluidized bed reactor, the catalyst regenerator is connected to the lower end of the separator, the lower end of the catalyst regenerator is connected to the lower part of the fluidized bed reactor, the feed pipe is connected to the lower end and the side of the fluidized bed reactor, and the feed pipe is evenly spaced and connected to the side of the fluidized bed reactor;

[0008] A propylene separation system, the propylene separation system being in communication with the separator and the feed pipe;

[0009] A propylene oxide purification system, wherein the propylene oxide purification system is connected to the propylene separation system;

[0010] A methanol recovery system, wherein the formaldehyde recovery system is connected to the propylene oxide purification system, and the methanol recovery system is also connected to the feed pipe.

[0011] In some embodiments of the present application, the propylene separation system comprises:

[0012] A high-pressure propylene stripping tower, wherein the lower portion of the high-pressure propylene stripping tower is connected to the separator, and the upper end of the high-pressure propylene stripping tower is connected to the feed pipe;

[0013] A low-pressure thermal separation tank, wherein the lower end of the high-pressure propylene stripping tower is connected to the side of the low-pressure thermal separation tank;

[0014] A low-pressure propylene stripping tower, a separation tank bottom liquid cooler and a circulating propylene compressor, wherein the upper end of the low-pressure hot separation tank is connected to the lower part of the low-pressure propylene stripping tower, the lower end of the low-pressure hot separation tank is connected to the upper part of the low-pressure propylene stripping tower through the separation tank bottom liquid cooler, the upper end of the low-pressure propylene stripping tower is connected to the upper part of the high-pressure propylene stripping tower through the circulating propylene compressor, and the lower end of the low-pressure propylene stripping tower is connected to the propylene oxide purification system.

[0015] In some embodiments of the present application, the propylene oxide purification system comprises:

[0016] A propylene oxide distillation tower, wherein the lower end of the low-pressure propylene stripping tower is connected to the propylene oxide distillation tower, and the lower end of the propylene oxide distillation tower is connected to the methanol recovery system;

[0017] An extractive distillation tower, wherein the upper end of the propylene oxide distillation tower is connected to the side of the extractive distillation tower, and the lower end of the extractive distillation tower is connected to the methanol recovery system;

[0018] The acetaldehyde removal tower, the upper end of the extractive distillation tower is connected to the side of the acetaldehyde removal tower.

[0019] In some embodiments of the present application, the methanol recovery system comprises:

[0020] A hydrogenation reactor, wherein the lower ends of the propylene oxide distillation tower and the extractive distillation tower are both connected to the hydrogenation reactor;

[0021] A low-pressure methanol distillation tower, wherein the hydrogenation reactor is connected to a side of the low-pressure methanol distillation tower, and the upper end of the low-pressure methanol distillation tower is connected to the feed pipe;

[0022] a high-pressure methanol distillation tower, wherein the lower end of the low-pressure methanol distillation tower is connected to the side of the high-pressure methanol distillation tower;

[0023] A methanol reflux tank, wherein the upper end and the upper part of the high-pressure methanol distillation tower are both connected to the methanol reflux tank.

[0024] In some embodiments of the present application, a high-pressure propylene stripping reboiler is provided at the lower portion of the high-pressure propylene stripping tower, and the upper end of the high-pressure methanol distillation tower is connected to the methanol reflux tank through the high-pressure propylene stripping reboiler; and / or,

[0025] A low-pressure propylene stripping reboiler is provided at the lower part of the low-pressure propylene stripping tower, and the upper end of the high-pressure methanol distillation tower is connected to the methanol reflux tank through the low-pressure propylene stripping reboiler; and / or,

[0026] A propylene oxide distillation reboiler is disposed at the lower part of the propylene oxide distillation tower, and the upper end of the high-pressure methanol distillation tower is connected to the methanol reflux tank through the propylene oxide distillation reboiler; and / or,

[0027] An extractive distillation reboiler is provided at the lower part of the extractive distillation tower, and the upper end of the extractive distillation tower is connected to the methanol reflux tank through the extractive distillation reboiler; and / or,

[0028] An acetaldehyde removal reboiler is provided at the lower part of the acetaldehyde removal tower, and the upper end of the acetaldehyde removal tower is connected to the methanol reflux tank through the acetaldehyde removal reboiler; and / or,

[0029] A low-pressure methanol distillation reboiler is provided at the lower part of the low-pressure methanol distillation tower, and the upper end of the low-pressure methanol distillation tower is connected to the methanol reflux tank through the low-pressure methanol distillation reboiler; and / or,

[0030] A high-pressure methanol distillation reboiler is arranged at the lower part of the high-pressure methanol distillation tower.

[0031] In a second aspect, an embodiment of the present application provides a method for producing propylene oxide, the method being implemented by the propylene oxide production device described in the first aspect, the method comprising the following steps:

[0032] Propylene from the propylene separation system, methanol from the methanol recovery system, and propylene, methanol, and hydrogen peroxide from the outside are introduced into the fluidized bed reactor through the feed pipe to carry out epoxidation reaction;

[0033] introducing the reaction product and the epoxidation catalyst in the fluidized bed reactor into the separator to separate the reaction product and the epoxidation catalyst;

[0034] introducing the separated epoxidation catalyst into the catalyst regenerator for treatment and then circulating it back to the fluidized bed reactor;

[0035] introducing the separated reaction product into the propylene separation system to separate propylene to obtain liquid crude propylene oxide and propylene, and introducing the separated propylene into the fluidized bed reactor;

[0036] introducing the crude propylene oxide into the propylene oxide purification system to purify the propylene oxide to obtain a propylene oxide product and a mixed solution containing methanol;

[0037] The mixed solution is introduced into the methanol recovery system for treatment to obtain methanol and alcohol ether wastewater. The obtained methanol is introduced into the fluidized bed reactor, and the alcohol ether wastewater is discharged.

[0038] In some embodiments of the present application, the reaction conditions of the fluidized bed reactor are as follows:

[0039] Temperature: 20~60℃;

[0040] Pressure: 1.6~3.5MPa;

[0041] Hydrogen peroxide mass air velocity 0.1~10.0hr -1 ;

[0042] The molar ratio of propylene to hydrogen peroxide is 1.2 to 5:1;

[0043] The molar ratio of methanol to hydrogen peroxide is 2 to 10:1.

[0044] In some embodiments of the present application, the reaction conditions of the fluidized bed reactor are as follows:

[0045] Temperature: 25-35℃;

[0046] Pressure: 2.4~3.0MPa;

[0047] Hydrogen peroxide mass air velocity 1.0~5.0hr -1 ;

[0048] The molar ratio of propylene to hydrogen peroxide is 1.5 to 3:1;

[0049] The molar ratio of methanol to hydrogen peroxide is 3 to 6:1.

[0050] In some embodiments of the present application, the concentration of the hydrogen peroxide is 27.5wt% to 70wt%; and / or,

[0051] In the hydrogen peroxide introduced into the fluidized bed reactor through the feed pipe, the mass percentage of the hydrogen peroxide introduced from the lower end of the fluidized bed reactor is 25% to 50%.

[0052] In some embodiments of the present application, the concentration of the hydrogen peroxide is 50wt% to 70wt%; and / or,

[0053] In the hydrogen peroxide introduced into the fluidized bed reactor through the feed pipe, the mass percentage of the hydrogen peroxide introduced from the lower end of the fluidized bed reactor is 40% to 50%.

[0054] In some embodiments of the present application, the operating pressure of the high-pressure propylene stripping tower is 1.2-1.5 MPa, the tower top temperature is 35-50° C., the tower bottom temperature is 60-80° C., and the number of theoretical plates is 10-20; and / or,

[0055] The low-pressure propylene stripping tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 35-45° C., a tower bottom temperature of 70-80° C., and a theoretical plate number of 10-15.

[0056] In some embodiments of the present application, the operating pressure of the propylene oxide distillation tower is 0.01-0.1 MPa, the tower top temperature is 45-70° C., the tower bottom temperature is 70-85° C., and the number of theoretical plates is 20-30; and / or,

[0057] The extractive distillation tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 35-50° C., a tower bottom temperature of 75-85° C., and a theoretical plate number of 45-60; and / or,

[0058] The operating pressure of the acetaldehyde removal tower is 0.1-0.3 MPa, the tower top temperature is 55-75° C., the tower bottom temperature is 65-80° C., and the number of theoretical plates is 40-65.

[0059] In some embodiments of the present application, the alcohol-water hydrogenation operation pressure is 2.5-4.0 MPa, and the reaction temperature is 100-150° C.; and / or,

[0060] A hydrogenation catalyst is arranged in the hydrogenation reactor, and the hydrogenation catalyst is a high-nickel catalyst or a noble metal catalyst; and / or,

[0061] The low-pressure methanol distillation tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 65-85° C., a tower bottom temperature of 75-90° C., and a theoretical plate number of 20-35; and / or,

[0062] The operating pressure of the high-pressure methanol distillation tower is 0.2-0.5 MPa, the tower top temperature is 100-120° C., the tower bottom temperature is 135-160° C., and the number of theoretical plates is 20-35.

[0063] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0064] The propylene oxide production device provided in the embodiment of the present application performs an epoxidation reaction of producing propylene oxide by the HPPO method in a fluidized bed reactor, wherein hydrogen peroxide enters the fluidized bed reactor from the lower end and the side of the fluidized bed reactor, and the hydrogen peroxide enters the fluidized bed reactor from the side of the fluidized bed reactor at uniform intervals, so that the concentration gradient of hydrogen peroxide in the reaction material is uniform, the reaction rate is uniform and controllable, and the occurrence of the "flying temperature" phenomenon is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0066] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0067] Figure 1 This is a schematic diagram of the structure of a propylene oxide production device provided in an embodiment of the present application.

[0068] The meanings of the numbers in the figure are as follows:

[0069] 1- fluidized bed reactor, 2- high-pressure propylene stripping tower, 3- high-pressure propylene stripping reboiler, 4- low-pressure hot separation tank, 5- separation tank bottom liquid cooler, 6- low-pressure propylene stripping tower, 7- circulating propylene compressor, 8- low-pressure propylene stripping reboiler, 9- propylene oxide distillation tower, 10- propylene oxide distillation reboiler, 11- extractive distillation tower, 12- extractive distillation reboiler, 13- acetaldehyde removal tower, 14- acetaldehyde removal reboiler, 15- hydrogenation reactor, 16- low-pressure methanol distillation tower, 17- low-pressure methanol reboiler, 18- high-pressure methanol distillation tower, 19- high-pressure methanol distillation reboiler, 20- methanol reflux tank, 21- separator, 22- catalyst regenerator DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0071] Unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the event of a conflict, this specification takes precedence.

[0072] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0073] The existing HPPO method for producing propylene oxide has technical problems such as difficult to control the reaction and prone to local "temperature runaway".

[0074] The technical solution provided by the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0075] In the first aspect, the present application embodiment provides a production device for propylene oxide, please refer to Figure 1 , the propylene oxide production device comprises:

[0076] A reaction system, the reaction system comprising a fluidized bed reactor 1, a feed pipe, a separator 21 and a catalyst regenerator 22, wherein the separator 21 is connected to the upper end of the fluidized bed reactor 1, the catalyst regenerator 22 is connected to the lower end of the separator 21, the lower end of the catalyst regenerator 22 is connected to the lower part of the fluidized bed reactor 1, the feed pipe is connected to the lower end and the side of the fluidized bed reactor 1, and the feed pipe is evenly spaced and connected to the side of the fluidized bed reactor 1;

[0077] A propylene separation system, the propylene separation system is connected to the separator 21 and the feed pipe;

[0078] A propylene oxide purification system, wherein the propylene oxide purification system is connected to the propylene separation system;

[0079] A methanol recovery system, wherein the formaldehyde recovery system is connected to the propylene oxide purification system, and the methanol recovery system is also connected to the feed pipe.

[0080] The propylene oxide production device described in the present application can be applied to the production of propylene oxide by the HPPO method. The raw materials of the HPPO method are hydrogen peroxide and propylene, and the solvent is generally methanol. A dispersion device is generally provided at the bottom of the fluidized bed reactor 1, for example, a microchannel dispersion device, and the function of the dispersion device is to mix the reaction raw materials entering from the lower end of the fluidized bed reactor 1 uniformly.

[0081] After the reaction raw materials are mixed evenly, they are mixed with the epoxidation catalyst from the catalyst regenerator 22 to form a slurry liquid that flows upward. In the slurry liquid state, the reaction materials are in close contact with the epoxidation catalyst, and rapid mass transfer is performed to cause an epoxidation reaction. The epoxidation reaction releases a large amount of reaction heat, and a heat collector can be set in the fluidized bed reactor 1 to take away the reaction heat. For example, the heat collector can be a submerged flow casing heat collector.

[0082] Hydrogen peroxide enters the fluidized bed reactor 1 from the lower end and the side of the fluidized bed reactor 1. The feed pipe is evenly spaced and connected to the side of the fluidized bed reactor 1, that is, the side of the fluidized bed reactor 1 is evenly spaced with hydrogen peroxide feed ports. The purpose of hydrogen peroxide segmented feeding is to ensure that the hydrogen peroxide concentration gradient in the reaction material is uniform and the reaction rate is uniform and controllable. It is easy to understand that the hydrogen peroxide segmented feeding is divided into at least two sections. In order to further refine the thermal management, the heat extractor can be set inside the fluidized bed reactor 1 above each hydrogen peroxide feed port.

[0083] The reaction slurry in the fluidized bed reactor 1 reaches the top of the reactor and enters the separator 21. In the separator 21, the slurry is broken, and the epoxidation catalyst is separated from the reaction product. The separator 21 discharges the reaction product to the propylene separation system. The bottom of the separator 21 is enriched with a concentrated slurry of epoxidation catalyst particles. The concentrated slurry flows out from the bottom of the separator 21 by gravity to the catalyst regenerator 22 for regeneration. In order to increase work efficiency and reduce waste, the catalyst regenerator 22 can only regenerate part of the epoxidation catalyst. For example, a lock hopper can be set at the bottom of the epoxidation catalyst regenerator 22. A part of the concentrated slurry enters the lock hopper after catalyst regeneration, and the other part directly enters the lock hopper. The epoxidation catalyst in the lock hopper is circulated back to the fluidized bed reactor 1.

[0084] The present application uses a fluidized bed reactor 1 to carry out an epoxidation reaction for producing propylene oxide by the HPPO method, wherein hydrogen peroxide enters the fluidized bed reactor 1 from the lower end and the side of the fluidized bed reactor 1, and the hydrogen peroxide enters the fluidized bed reactor 1 from the side of the fluidized bed reactor 1 at uniform intervals, so that the concentration gradient of hydrogen peroxide in the reaction material is uniform, the reaction rate is uniform and controllable, and the occurrence of local "hot spots" is avoided.

[0085] In some embodiments of the present application, the propylene separation system comprises:

[0086] A high-pressure propylene stripping tower 2, wherein the lower portion of the high-pressure propylene stripping tower 2 is connected to the separator 21, and the upper end of the high-pressure propylene stripping tower 2 is connected to the feed pipe;

[0087] A low-pressure thermal separation tank 4, wherein the lower end of the high-pressure propylene stripping tower 2 is connected to the side of the low-pressure thermal separation tank 4;

[0088] A low-pressure propylene stripping tower 6, a separation tank bottom liquid cooler 5 and a circulating propylene compressor 7, the upper end of the low-pressure hot separation tank 4 is connected to the lower part of the low-pressure propylene stripping tower 6, the lower end of the low-pressure hot separation tank 4 is connected to the upper part of the low-pressure propylene stripping tower 6 through the separation tank bottom liquid cooler 5, the upper end of the low-pressure propylene stripping tower 6 is connected to the upper part of the high-pressure propylene stripping tower 2 through the circulating propylene compressor 7, and the lower end of the low-pressure propylene stripping tower 6 is connected to the propylene oxide purification system.

[0089] The reaction products contain oxygen, propylene oxide, propylene, with or without propane, methanol, water, with or without hydrogen peroxide, propylene glycol monomethyl ether, propylene glycol, and a small amount of aldehyde and ketone impurities.

[0090] The purpose of separating propylene from the reaction product by the two devices of high-pressure propylene stripping tower 2 and low-pressure propylene stripping tower 6 is to control a lower temperature during the propylene separation process and inhibit the hydrolysis side reaction of propylene oxide. Due to the existence of the low-pressure propylene stripping tower 6, the high-pressure propylene stripping tower 2 only needs to separate a part of the propylene. Generally, in practical applications, only 60%-80% of the propylene is recovered. The remaining reaction product containing propylene enters the low-pressure hot separation tank 4, the gas phase at the top of the tank enters the lower end of the low-pressure propylene stripping tower 6, and the liquid phase at the bottom of the tank is cooled by the separation tank bottom liquid cooler 5 and then enters the upper end of the low-pressure propylene stripping tower 6, and is used as an absorption liquid to wash the impurities in the propylene from top to bottom.

[0091] The high-pressure propylene stripping tower 2 performs pre-separation on propylene, and the high-purity propylene separated from the top of the tower is sent back to the reactor to continue to participate in the reaction. The remaining propylene, water, propylene oxide, methanol, propylene glycol monomethyl ether, propylene glycol, and a small amount of materials containing or not containing hydrogen peroxide and aldehyde ketone impurities are obtained at the bottom of the tower and sent to the low-pressure hot separation tank 4. The crude propylene is pre-flashed from the top of the tank and sent to the bottom of the low-pressure propylene stripping tower 6. The liquid cooler 5 at the bottom of the separation tank enters the top of the low-pressure propylene stripping tower 6 to absorb and wash propylene. The propylene with higher purity obtained from the top of the low-pressure propylene stripping tower 6 is returned to the lower part of the high-pressure propylene stripping tower 2 for recovery after being pressurized by the compressor.

[0092] At present, the purification of propylene oxide is usually completed in three steps: the first step is to use a distillation tower to separate the reaction product into a tower top material containing propylene oxide, propylene, propane and oxygen and a tower bottom material containing solvent, water and high-boiling impurities. The solvent and water are treated by hydrogenation and then the solvent is recovered by a distillation process; the second step is to separate the light components containing propylene and propane at the top of the distillation tower, and the bottom of the tower is crude propylene oxide containing water and solvent. The propylene is stripped and refined and returned to the reactor for recycling; the third step is to extract and separate the crude propylene oxide, and obtain the propylene oxide product at the top of the tower. The entire process is long, the distillation tower uses a large amount of heat medium, the device has high energy consumption, and the propylene oxide is at a high ambient temperature during the separation process. It cannot be separated from water and solvent in time, which accelerates the hydrolysis reaction of propylene oxide, the amount of by-products is large, and the yield of propylene oxide is low.

[0093] However, the present application does not directly separate the propylene oxide in the reaction product, but first separates only propylene, and separates propylene at a relatively low temperature by combining a high-pressure propylene stripping tower 2, a low-pressure hot separation tank 4, and a low-pressure propylene stripping tower 6, and then separates propylene oxide separately. The temperature of the propylene oxide as a whole is relatively low, the hydrolysis side reaction is suppressed, the by-products are less, and the yield of propylene oxide is high.

[0094] In some embodiments of the present application, the propylene oxide purification system comprises:

[0095] A propylene oxide distillation tower 9, wherein the lower end of the low-pressure propylene stripping tower 6 is connected to the propylene oxide distillation tower 9, and the lower end of the propylene oxide distillation tower 9 is connected to the methanol recovery system;

[0096] An extractive distillation tower 11, wherein the upper end of the propylene oxide distillation tower 9 is connected to the side of the extractive distillation tower 11, and the lower end of the extractive distillation tower 11 is connected to the methanol recovery system;

[0097] The acetaldehyde removal tower 13 , the upper end of the extractive distillation tower 11 is connected to the side of the acetaldehyde removal tower 13 .

[0098] The water, propylene oxide, methanol, propylene glycol monomethyl ether, propylene glycol, and a small amount of materials containing or not containing hydrogen peroxide and aldehydes and ketones impurities obtained at the bottom of the low-pressure propylene stripping tower 6 are sent to the propylene oxide distillation tower 9, and propylene oxide, methanol, and a small amount of water are obtained at the top of the tower, and water, methanol, propylene glycol monomethyl ether, propylene glycol, and a small amount of materials containing or not containing hydrogen peroxide and aldehydes and ketones impurities are obtained at the bottom of the tower. The top material of the propylene oxide distillation tower 9 is sent to the extraction distillation tower 11, and the extractant can be selected from at least one of desalted water, deoxygenated water or steam turbine condensate water. Through the operation of the extraction distillation tower 11, a high-purity propylene oxide product is obtained at the top of the tower, and then sent to the acetaldehyde removal tower 13 to remove a small amount of aldehyde in the propylene oxide product, and a 99.99% propylene oxide product is obtained at the bottom of the acetaldehyde removal tower 13. The bottom product of the extractive distillation tower 11 is basically methanol, water, and a small amount of propylene oxide, which is sent to the methanol recovery system together with the bottom material of the propylene oxide distillation tower 9.

[0099] In some embodiments of the present application, the methanol recovery system comprises:

[0100] A hydrogenation reactor 15, the lower ends of the propylene oxide distillation tower 9 and the extractive distillation tower 11 are both connected to the hydrogenation reactor 15;

[0101] A low-pressure methanol distillation tower 16, wherein the hydrogenation reactor 15 is connected to a side of the low-pressure methanol distillation tower 16, and an upper end of the low-pressure methanol distillation tower 16 is connected to the feed pipe;

[0102] A high-pressure methanol distillation tower 18, wherein the lower end of the low-pressure methanol distillation tower 16 is connected to the side of the high-pressure methanol distillation tower 18;

[0103] The methanol reflux tank 20 , the upper end and the upper part of the high-pressure methanol distillation tower 18 are both connected to the methanol reflux tank 20 .

[0104] Water, methanol, propylene glycol monomethyl ether, propylene glycol, and a small amount of materials containing or not containing hydrogen peroxide and aldehyde and ketone impurities obtained at the bottom of propylene oxide distillation tower 9 and extractive distillation tower 11 are hydrogenated to remove aldehydes, ketones and excess hydrogen peroxide, and the alcohol water material obtained by hydrogenation contains water, methanol, propylene glycol monomethyl ether and propylene glycol. The alcohol water material first enters the low-pressure methanol tower, and the tower top obtains methanol with a purity of 99%wt. The tower bottom obtains the material containing water, residual methanol, propylene glycol monomethyl ether and propylene glycol and is sent to the high-pressure methanol tower to recycle the residual methanol, and the tower top obtains methanol with a purity of 99%wt. The tower bottom obtains the material containing water, propylene glycol monomethyl ether and propylene glycol, which is discharged as alcohol ether wastewater.

[0105] In some embodiments of the present application, a high-pressure propylene stripping reboiler 3 is provided at the lower portion of the high-pressure propylene stripping tower 2, and the upper end of the high-pressure methanol distillation tower 18 is connected to the methanol reflux tank 20 through the high-pressure propylene stripping reboiler 3; and / or,

[0106] A low-pressure propylene stripping reboiler 8 is provided at the lower part of the low-pressure propylene stripping tower 6, and the upper end of the high-pressure methanol distillation tower 18 is connected to the methanol reflux tank 20 through the low-pressure propylene stripping reboiler 8; and / or,

[0107] A propylene oxide distillation reboiler 10 is disposed at the lower part of the propylene oxide distillation tower 9, and the upper end of the high-pressure methanol distillation tower 18 is connected to the methanol reflux tank 20 through the propylene oxide distillation reboiler 10; and / or,

[0108] An extractive distillation reboiler 12 is disposed at the lower portion of the extractive distillation tower 11, and the upper end of the extractive distillation tower 11 is connected to the methanol reflux tank 20 through the extractive distillation reboiler 12; and / or,

[0109] The lower part of the acetaldehyde removal tower 13 is provided with an acetaldehyde removal reboiler 14, and the upper end of the acetaldehyde removal tower 13 is connected to the methanol reflux tank 20 through the acetaldehyde removal reboiler 14; and / or,

[0110] A low-pressure methanol distillation reboiler is disposed at the lower part of the low-pressure methanol distillation tower 16, and the upper end of the low-pressure methanol distillation tower 16 is connected to the methanol reflux tank 20 through the low-pressure methanol distillation reboiler; and / or,

[0111] A high-pressure methanol distillation reboiler 19 is disposed at the lower portion of the high-pressure methanol distillation tower 18 .

[0112] The gas phase at the top of the high-pressure methanol tower is 99%wt methanol, which is respectively connected to the high-pressure propylene stripping reboiler 3, the low-pressure propylene stripping reboiler 8, the propylene oxide distillation reboiler 10, the extractive distillation reboiler 12, the acetaldehyde removal reboiler 14 and the low-pressure methanol reboiler 17, and is condensed into liquid methanol and then returned to the reaction system for recycling. The gas phase methanol at the top of the high-pressure methanol tower condenses into liquid methanol, which can generate a large amount of phase change heat as a heat source for reboiling in each tower. The present application deeply integrates the high-pressure methanol tower with the remaining distillation towers into a heat system, and only the high-pressure methanol tower is heated by an external heat source, and the heat sources of the remaining towers are provided by the gas phase at the top of the high-pressure methanol tower, which greatly reduces the energy consumption of the device.

[0113] In a second aspect, an embodiment of the present application provides a method for producing propylene oxide, the method being implemented by the propylene oxide production device described in the first aspect, the method comprising the following steps:

[0114] S1: introducing propylene from the propylene separation system, methanol from the methanol recovery system, and propylene, methanol, and hydrogen peroxide from the outside into the fluidized bed reactor 1 through the feed pipe to perform an epoxidation reaction;

[0115] S2: introducing the reaction product and the epoxidation catalyst in the fluidized bed reactor 1 into the separator 21 to separate the reaction product and the epoxidation catalyst;

[0116] S3: introducing the separated epoxidation catalyst into the catalyst regenerator 22 for treatment, and then circulating it back to the fluidized bed reactor 1;

[0117] S4: introducing the separated reaction product into the propylene separation system to separate propylene to obtain liquid crude propylene oxide and propylene, and introducing the separated propylene into the fluidized bed reactor 1;

[0118] S5: introducing the crude propylene oxide into the propylene oxide purification system to purify the propylene oxide to obtain a propylene oxide product and a mixed solution containing methanol;

[0119] S6: The mixed solution is introduced into the methanol recovery system for treatment to obtain methanol and alcohol ether wastewater, the obtained methanol is introduced into the fluidized bed reactor 1, and the alcohol ether wastewater is discharged.

[0120] It is easy to understand that the method described in the present application is carried out by the propylene oxide production device described in the present application. In the propylene oxide production device, the feed pipe is connected to the lower end and the side of the fluidized bed reactor 1, and the feed pipe is evenly spaced and connected to the side of the fluidized bed reactor 1. Therefore, the method described in the present application can allow hydrogen peroxide to enter the fluidized bed reactor 1 from the lower end and the side of the fluidized bed reactor 1, and hydrogen peroxide enters the fluidized bed reactor 1 from the side of the fluidized bed reactor 1 at even intervals, which makes the concentration gradient of hydrogen peroxide in the reaction material uniform, the reaction rate is uniform and controllable, and the occurrence of local "hot spots" is avoided.

[0121] By implementing the method described in the present application with the propylene oxide production device described in the present application, the utilization rate of hydrogen peroxide reaches more than 99.99%, the selectivity of propylene oxide reaches more than 98.7%, and the purity of the propylene oxide product is high, reaching 99.99%.

[0122] In some embodiments of the present application, the reaction conditions of the fluidized bed reactor 1 are as follows:

[0123] Temperature: 20~60℃;

[0124] Pressure: 1.6~3.5MPa;

[0125] Hydrogen peroxide mass air velocity 0.1~10.0hr -1 ;

[0126] The molar ratio of propylene to hydrogen peroxide is 1.2 to 5:1;

[0127] The molar ratio of methanol to hydrogen peroxide is 2 to 10:1.

[0128] In some embodiments of the present application, the reaction conditions of the fluidized bed reactor 1 are as follows:

[0129] Temperature: 25-35℃;

[0130] Pressure: 2.4~3.0MPa;

[0131] Hydrogen peroxide mass air velocity 1.0~5.0hr -1 ;

[0132] The molar ratio of propylene to hydrogen peroxide is 1.5 to 3:1;

[0133] The molar ratio of methanol to hydrogen peroxide is 3 to 6:1.

[0134] In some embodiments of the present application, the concentration of the hydrogen peroxide is 27.5wt% to 70wt%; and / or,

[0135] Among the hydrogen peroxide introduced into the fluidized bed reactor 1 through the feed pipe, the mass percentage of the hydrogen peroxide introduced from the lower end of the fluidized bed reactor 1 is 25% to 50%.

[0136] In some embodiments of the present application, the concentration of the hydrogen peroxide is 50wt% to 70wt%; and / or,

[0137] Among the hydrogen peroxide introduced into the fluidized bed reactor 1 through the feed pipe, the mass percentage of the hydrogen peroxide introduced from the lower end of the fluidized bed reactor 1 is 40% to 50%.

[0138] In some embodiments of the present application, the operating pressure of the high-pressure propylene stripping tower 2 is 1.2-1.5 MPa, the tower top temperature is 35-50° C., the tower bottom temperature is 60-80° C., and the number of theoretical plates is 10-20; and / or,

[0139] The low-pressure propylene stripping tower 6 has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 35-45° C., a tower bottom temperature of 70-80° C., and a theoretical plate number of 10-15.

[0140] In some embodiments of the present application, the operating pressure of the propylene oxide distillation tower 9 is 0.01-0.1 MPa, the tower top temperature is 45-70° C., the tower bottom temperature is 70-85° C., and the number of theoretical plates is 20-30; and / or,

[0141] The extractive distillation tower 11 has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 35-50° C., a tower bottom temperature of 75-85° C., and a theoretical plate number of 45-60; and / or,

[0142] The acetaldehyde removal tower 13 has an operating pressure of 0.1-0.3 MPa, a tower top temperature of 55-75° C., a tower bottom temperature of 65-80° C., and a theoretical plate number of 40-65.

[0143] In some embodiments of the present application, the alcohol-water hydrogenation operation pressure is 2.5-4.0 MPa, and the reaction temperature is 100-150° C.; and / or,

[0144] The hydrogenation reactor 15 is provided with a hydrogenation catalyst, wherein the hydrogenation catalyst is a high-nickel catalyst or a noble metal catalyst; and / or,

[0145] The low-pressure methanol distillation tower 16 has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 65-85° C., a tower bottom temperature of 75-90° C., and a theoretical plate number of 20-35; and / or,

[0146] The operating pressure of the high-pressure methanol distillation tower 18 is 0.2-0.5 MPa, the tower top temperature is 100-120° C., the tower bottom temperature is 135-160° C., and the number of theoretical plates is 20-35.

[0147] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0148] Example 1

[0149] First, this embodiment provides a production device for propylene oxide, please refer to Figure 1 , the propylene oxide production device comprises:

[0150] A reaction system, the reaction system comprising a fluidized bed reactor 1, a feed pipe, a separator 21 and a catalyst regenerator 22, wherein the separator 21 is connected to the upper end of the fluidized bed reactor 1, the catalyst regenerator 22 is connected to the lower end of the separator 21, the lower end of the catalyst regenerator 22 is connected to the lower part of the fluidized bed reactor 1, the feed pipe is connected to the lower end and the side of the fluidized bed reactor 1, and the feed pipe is evenly spaced and connected to the side of the fluidized bed reactor 1;

[0151] A propylene separation system, the propylene separation system is connected to the separator 21 and the feed pipe;

[0152] A propylene oxide purification system, wherein the propylene oxide purification system is connected to the propylene separation system;

[0153] A methanol recovery system, wherein the formaldehyde recovery system is connected to the propylene oxide purification system, and the methanol recovery system is also connected to the feed pipe.

[0154] The propylene separation system comprises:

[0155] A high-pressure propylene stripping tower 2, wherein the lower portion of the high-pressure propylene stripping tower 2 is connected to the separator 21, and the upper end of the high-pressure propylene stripping tower 2 is connected to the feed pipe;

[0156] A low-pressure thermal separation tank 4, wherein the lower end of the high-pressure propylene stripping tower 2 is connected to the side of the low-pressure thermal separation tank 4;

[0157] A low-pressure propylene stripping tower 6, a separation tank bottom liquid cooler 5 and a circulating propylene compressor 7, the upper end of the low-pressure hot separation tank 4 is connected to the lower part of the low-pressure propylene stripping tower 6, the lower end of the low-pressure hot separation tank 4 is connected to the upper part of the low-pressure propylene stripping tower 6 through the separation tank bottom liquid cooler 5, the upper end of the low-pressure propylene stripping tower 6 is connected to the upper part of the high-pressure propylene stripping tower 2 through the circulating propylene compressor 7, and the lower end of the low-pressure propylene stripping tower 6 is connected to the propylene oxide purification system.

[0158] The propylene oxide purification system comprises:

[0159] A propylene oxide distillation tower 9, wherein the lower end of the low-pressure propylene stripping tower 6 is connected to the propylene oxide distillation tower 9, and the lower end of the propylene oxide distillation tower 9 is connected to the methanol recovery system;

[0160] An extractive distillation tower 11, wherein the upper end of the propylene oxide distillation tower 9 is connected to the side of the extractive distillation tower 11, and the lower end of the extractive distillation tower 11 is connected to the methanol recovery system;

[0161] The acetaldehyde removal tower 13 , the upper end of the extractive distillation tower 11 is connected to the side of the acetaldehyde removal tower 13 .

[0162] The methanol recovery system comprises:

[0163] A hydrogenation reactor 15, the lower ends of the propylene oxide distillation tower 9 and the extractive distillation tower 11 are both connected to the hydrogenation reactor 15;

[0164] A low-pressure methanol distillation tower 16, wherein the hydrogenation reactor 15 is connected to a side of the low-pressure methanol distillation tower 16, and an upper end of the low-pressure methanol distillation tower 16 is connected to the feed pipe;

[0165] A high-pressure methanol distillation tower 18, wherein the lower end of the low-pressure methanol distillation tower 16 is connected to the side of the high-pressure methanol distillation tower 18;

[0166] The methanol reflux tank 20 , the upper end and the upper part of the high-pressure methanol distillation tower 18 are both connected to the methanol reflux tank 20 .

[0167] A high-pressure propylene stripping reboiler 3 is provided at the lower part of the high-pressure propylene stripping tower 2, and the upper end of the high-pressure methanol distillation tower 18 is connected to the methanol reflux tank 20 through the high-pressure propylene stripping reboiler 3;

[0168] A low-pressure propylene stripping reboiler 8 is provided at the lower part of the low-pressure propylene stripping tower 6, and the upper end of the high-pressure methanol distillation tower 18 is connected to the methanol reflux tank 20 through the low-pressure propylene stripping reboiler 8;

[0169] A propylene oxide distillation reboiler 10 is provided at the lower part of the propylene oxide distillation tower 9, and the upper end of the high-pressure methanol distillation tower 18 is connected to the methanol reflux tank 20 through the propylene oxide distillation reboiler 10;

[0170] An extractive distillation reboiler 12 is provided at the lower part of the extractive distillation tower 11, and the upper end of the extractive distillation tower 11 is connected to the methanol reflux tank 20 through the extractive distillation reboiler 12;

[0171] The lower part of the acetaldehyde removal tower 13 is provided with an acetaldehyde removal reboiler 14, and the upper end of the acetaldehyde removal tower 13 is connected to the methanol reflux tank 20 through the acetaldehyde removal reboiler 14;

[0172] A low-pressure methanol distillation reboiler is provided at the lower part of the low-pressure methanol distillation tower 16, and the upper end of the low-pressure methanol distillation tower 16 is connected to the methanol reflux tank 20 through the low-pressure methanol distillation reboiler;

[0173] A high-pressure methanol distillation reboiler 19 is disposed at the lower portion of the high-pressure methanol distillation tower 18 .

[0174] The present application also produces propylene oxide by the above-mentioned propylene oxide production device, and the method is as follows:

[0175] Reaction raw materials are provided, wherein the volume content of propylene in the gas raw material is 99.6%, the concentration of hydrogen peroxide in the reaction raw material is 50%, methanol is used as a solvent, and the molar ratio of hydrogen peroxide, propylene and methanol is 1:2:3.5.

[0176] The upflow fluidized bed reactor 1 has a diameter of 3000 mm and a height of 20 m. The interior is divided into four sections. Each section is provided with a submerged tube heat exchanger of the same specification. The refrigerant medium of the submerged tube heat exchanger is chilled water, and the chilled water supply temperature is 7°C. The lower part of each submerged tube heat exchanger is connected to the feed pipe at the side of the fluidized bed reactor 1. The hydrogen peroxide feed temperature is 25°C, the reaction temperature in the fluidized bed reactor 1 is 35°C, and the reaction pressure is 2.5 MPa. The hydrogen peroxide feed mass at the bottom of the fluidized bed reactor 1 is 50% of the total hydrogen peroxide feed mass, and the hydrogen peroxide feed mass at the side of the fluidized bed reactor 1 is 20%, 15%, 10% and 5% of the total hydrogen peroxide feed mass from bottom to top. After the reaction is completed, the utilization rate of hydrogen peroxide and the selectivity of propylene oxide are calculated. The results show that the utilization rate of hydrogen peroxide is 99.99% and the selectivity of propylene oxide is 98.7%. According to the composition of the reaction product analysis, the process described in this embodiment was calculated using the Aspen Plus simulation program. The composition of the reaction product at the outlet of the fluidized bed reactor of this embodiment is shown in Table 1, and the operating conditions of each tower of this embodiment are shown in Table 2.

[0177]

[0178]

[0179] Table 1 Example Reaction Product Composition

[0180]

[0181] Table 2 Example tower operating conditions

[0182] The propylene recovery rate in the high-pressure propylene stripping tower is 40%, the propylene purity recycled from the upper end of the high-pressure propylene stripping tower to the fluidized bed reactor is 99.5wt%, the methanol recovery rate in the bottom material of the low-pressure methanol distillation tower is 82%, and the methanol purity recycled from the methanol reflux tank to the fluidized bed reactor is 99wt%. The external heat medium input load is 56.17MW. The quality of the obtained PO product is 99.99% (weight) and the recovery rate is 99.6%.

[0183] Comparative Example 1

[0184] The difference between this comparative example and Example 1 is only that:

[0185] In this comparative example, the entire reaction system is replaced with a tubular fixed bed reactor.

[0186]

[0187]

[0188] Table 3 Comparative Example Reaction Product Composition

[0189] This comparative example adopts a tubular fixed bed reactor, and the results show that the by-products propylene glycol methyl ether and propylene glycol constitute 0.63%wt, the utilization rate of hydrogen peroxide is 96.13%, the selectivity of propylene oxide is 95%, the selectivity of propylene oxide is reduced by 3.7% compared with the implementation case, the side reaction products increase, and the propylene oxide yield is reduced by about 2%.

[0190] Comparative Example 2

[0191] The difference between this comparative example and the embodiment is only that:

[0192] This comparative example does not include a low-pressure hot separation tank, a low-pressure propylene stripping tower, a separation tank bottom liquid cooler, and a circulating propylene compressor, and the lower end of the high-pressure propylene stripping tower is directly connected to the propylene oxide purification system;

[0193] The operating conditions of each tower are shown in Table 4:

[0194]

[0195]

[0196] Table 4 Comparative Example 2 Tower Operating Conditions

[0197] The external heat medium input load of this comparative case is 66.17MW, and the energy consumption increases by 17.8% compared with the implementation case. The bottom temperature of the high-pressure propylene stripping tower reaches 133°C, the hydrolysis reaction rate of propylene oxide increases, and the yield of propylene oxide decreases.

[0198] Comparative Example 3

[0199] The difference between this comparative example and the embodiment is only that:

[0200] This comparative example does not have a high-pressure methanol distillation tower, and the upper end of the low-pressure methanol distillation tower is connected to a methanol reflux tank. The high-pressure propylene stripping reboiler, the low-pressure propylene stripping reboiler, the propylene oxide distillation reboiler, the extractive distillation reboiler, the acetaldehyde removal reboiler, and the low-pressure methanol distillation reboiler are all powered by external steam.

[0201] The operating conditions of each tower are shown in Table 5:

[0202] project Tower top / bottom temperature (℃) Pressure(MPa.G) Reboiler load (MW) High pressure propylene stripper 70 / 133 1.5 27.97 Propylene oxide distillation tower 66 / 84 0.04 13.88 Extractive distillation column 44 / 87 0.04 9.17 Acetaldehyde removal tower 59 / 73 0.2 4.85 Low pressure methanol distillation tower 75 / 170 0.05 7.97

[0203] Table 5 Comparative Example 3 Tower Operating Conditions

[0204] According to statistics, the external input load of this comparative example is 122.56MW. Compared with this comparative example, the embodiment can save 66.39MW of energy and reduce energy consumption by 54.17%.

[0205] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0206] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. refer to "including but not limited to". Moreover, the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of these three associated objects can exist alone, or any at least two of them exist at the same time. For example, for A, and / or B, and / or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, wherein a, b, and c can be single or multiple, respectively.

[0207] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A production device for propylene oxide, characterized in that: The production device of propylene oxide comprises: A reaction system, the reaction system comprising a fluidized bed reactor, a feed pipe, a separator and a catalyst regenerator, wherein the separator is connected to the upper end of the fluidized bed reactor, the catalyst regenerator is connected to the lower end of the separator, the lower end of the catalyst regenerator is connected to the lower part of the fluidized bed reactor, the feed pipe is connected to the lower end and the side of the fluidized bed reactor, and the feed pipe is evenly spaced and connected to the side of the fluidized bed reactor; A propylene separation system, the propylene separation system being in communication with the separator and the feed pipe; A propylene oxide purification system, wherein the propylene oxide purification system is connected to the propylene separation system; A methanol recovery system, wherein the formaldehyde recovery system is connected to the propylene oxide purification system, and the methanol recovery system is also connected to the feed pipe.

2. The production device of propylene oxide according to claim 1, characterized in that: The propylene separation system comprises: A high-pressure propylene stripping tower, wherein the lower portion of the high-pressure propylene stripping tower is connected to the separator, and the upper end of the high-pressure propylene stripping tower is connected to the feed pipe; A low-pressure thermal separation tank, wherein the lower end of the high-pressure propylene stripping tower is connected to the side of the low-pressure thermal separation tank; A low-pressure propylene stripping tower, a separation tank bottom liquid cooler and a circulating propylene compressor, wherein the upper end of the low-pressure hot separation tank is connected to the lower part of the low-pressure propylene stripping tower, the lower end of the low-pressure hot separation tank is connected to the upper part of the low-pressure propylene stripping tower through the separation tank bottom liquid cooler, the upper end of the low-pressure propylene stripping tower is connected to the upper part of the high-pressure propylene stripping tower through the circulating propylene compressor, and the lower end of the low-pressure propylene stripping tower is connected to the propylene oxide purification system.

3. The production device of propylene oxide according to claim 2, characterized in that: The propylene oxide purification system comprises: A propylene oxide distillation tower, wherein the lower end of the low-pressure propylene stripping tower is connected to the propylene oxide distillation tower, and the lower end of the propylene oxide distillation tower is connected to the methanol recovery system; An extractive distillation tower, wherein the upper end of the propylene oxide distillation tower is connected to the side of the extractive distillation tower, and the lower end of the extractive distillation tower is connected to the methanol recovery system; The acetaldehyde removal tower, the upper end of the extractive distillation tower is connected to the side of the acetaldehyde removal tower.

4. The production device of propylene oxide according to claim 3, characterized in that: The methanol recovery system comprises: A hydrogenation reactor, wherein the lower ends of the propylene oxide distillation tower and the extractive distillation tower are both connected to the hydrogenation reactor; A low-pressure methanol distillation tower, wherein the hydrogenation reactor is connected to a side of the low-pressure methanol distillation tower, and the upper end of the low-pressure methanol distillation tower is connected to the feed pipe; a high-pressure methanol distillation tower, wherein the lower end of the low-pressure methanol distillation tower is connected to the side of the high-pressure methanol distillation tower; A methanol reflux tank, wherein the upper end and the upper part of the high-pressure methanol distillation tower are both connected to the methanol reflux tank.

5. The production device of propylene oxide according to claim 4, characterized in that: A high-pressure propylene stripping reboiler is disposed at the lower part of the high-pressure propylene stripping tower, and the upper end of the high-pressure methanol distillation tower is connected to the methanol reflux tank through the high-pressure propylene stripping reboiler; and / or, A low-pressure propylene stripping reboiler is provided at the lower part of the low-pressure propylene stripping tower, and the upper end of the high-pressure methanol distillation tower is connected to the methanol reflux tank through the low-pressure propylene stripping reboiler; and / or, A propylene oxide distillation reboiler is disposed at the lower part of the propylene oxide distillation tower, and the upper end of the high-pressure methanol distillation tower is connected to the methanol reflux tank through the propylene oxide distillation reboiler; and / or, An extractive distillation reboiler is provided at the lower part of the extractive distillation tower, and the upper end of the extractive distillation tower is connected to the methanol reflux tank through the extractive distillation reboiler; and / or, An acetaldehyde removal reboiler is provided at the lower part of the acetaldehyde removal tower, and the upper end of the acetaldehyde removal tower is connected to the methanol reflux tank through the acetaldehyde removal reboiler; and / or, A low-pressure methanol distillation reboiler is provided at the lower part of the low-pressure methanol distillation tower, and the upper end of the low-pressure methanol distillation tower is connected to the methanol reflux tank through the low-pressure methanol distillation reboiler; and / or, A high-pressure methanol distillation reboiler is arranged at the lower part of the high-pressure methanol distillation tower.

6. A method for producing propylene oxide, characterized in that: The method is implemented by the propylene oxide production device according to any one of claims 4 to 5, and the method comprises the following steps: Propylene from the propylene separation system, methanol from the methanol recovery system, and propylene, methanol, and hydrogen peroxide from the outside are introduced into the fluidized bed reactor through the feed pipe to carry out epoxidation reaction; introducing the reaction product and the epoxidation catalyst in the fluidized bed reactor into the separator to separate the reaction product and the epoxidation catalyst; introducing the separated epoxidation catalyst into the catalyst regenerator for treatment and then circulating it back to the fluidized bed reactor; introducing the separated reaction product into the propylene separation system to separate propylene to obtain crude propylene oxide and propylene, and introducing the separated propylene into the fluidized bed reactor; introducing the crude propylene oxide into the propylene oxide purification system to purify the propylene oxide to obtain a propylene oxide product and a mixed solution containing methanol; The mixed solution is introduced into the methanol recovery system for treatment to obtain methanol and alcohol ether wastewater. The obtained methanol is introduced into the fluidized bed reactor, and the alcohol ether wastewater is discharged.

7. The method for producing propylene oxide according to claim 6, characterized in that: The reaction conditions of the fluidized bed reactor are as follows: Temperature: 20~60℃; Pressure: 1.6~3.5MPa; Hydrogen peroxide mass air velocity 0.1~10.0hr -1 ; The molar ratio of propylene to hydrogen peroxide is 1.2 to 5:1; The molar ratio of methanol to hydrogen peroxide is 2 to 10:

1.

8. The method for producing propylene oxide according to claim 7, characterized in that: The reaction conditions of the fluidized bed reactor are as follows: Temperature: 25-35℃; Pressure: 2.4~3.0MPa; Hydrogen peroxide mass air velocity 1.0~5.0hr -1 ; The molar ratio of propylene to hydrogen peroxide is 1.5 to 3:1; The molar ratio of methanol to hydrogen peroxide is 3 to 6:

1.

9. The method for producing propylene oxide according to claim 6, characterized in that: The concentration of the hydrogen peroxide is 27.5wt% to 70wt%; and / or, In the hydrogen peroxide introduced into the fluidized bed reactor through the feed pipe, the mass percentage of the hydrogen peroxide introduced from the lower end of the fluidized bed reactor is 25% to 50%.

10. The method for producing propylene oxide according to claim 9, characterized in that: The concentration of the hydrogen peroxide is 50wt% to 70wt%; and / or, In the hydrogen peroxide introduced into the fluidized bed reactor through the feed pipe, the mass percentage of the hydrogen peroxide introduced from the lower end of the fluidized bed reactor is 40% to 50%.

11. The method for producing propylene oxide according to claim 6, characterized in that: The operating pressure of the high-pressure propylene stripping tower is 1.2-1.5 MPa, the tower top temperature is 35-50° C., the tower bottom temperature is 60-80° C., and the number of theoretical plates is 10-20; and / or, The low-pressure propylene stripping tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 35-45° C., a tower bottom temperature of 70-80° C., and a theoretical plate number of 10-15.

12. The method for producing propylene oxide according to claim 6, characterized in that: The propylene oxide distillation tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 45-70° C., a tower bottom temperature of 70-85° C., and a theoretical plate number of 20-30; and / or, The extractive distillation tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 35-50° C., a tower bottom temperature of 75-85° C., and a theoretical plate number of 45-60; and / or, The operating pressure of the acetaldehyde removal tower is 0.1-0.3 MPa, the tower top temperature is 55-75° C., the tower bottom temperature is 65-80° C., and the number of theoretical plates is 40-65.

13. The method for producing propylene oxide according to claim 6, characterized in that: The alcohol-water hydrogenation operation pressure is 2.5-4.0 MPa, and the reaction temperature is 100-150° C.; and / or, A hydrogenation catalyst is arranged in the hydrogenation reactor, and the hydrogenation catalyst is a high-nickel catalyst or a noble metal catalyst; and / or, The low-pressure methanol distillation tower has an operating pressure of 0.01-0.1 MPa, a tower top temperature of 65-85° C., a tower bottom temperature of 75-90° C., and a theoretical plate number of 20-35; and / or, The operating pressure of the high-pressure methanol distillation tower is 0.2-0.5 MPa, the tower top temperature is 100-120° C., the tower bottom temperature is 135-160° C., and the number of theoretical plates is 20-35.

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